Variable area fuel nozzle



Oct. M, 1952 T c. NOON ET AL 2,613,998

VARIABLE. AREA FUEL NozzLE Filed sept. 15, 194e 2 SHEETS- SHEET 1.

zgf 544 fg-6 2a 50 27 Oct. 14, 1952 T c. NOON ET Al. 2,613,998

VARIABLE AREA FUEL NozzLE Filed sept. 15, 1948 2 SHEETS- SHEET 2 Ihr/E n Tar/:-

gZ/,ZML /MM 2% Patented Oct. 14, 1952 UNITED STATES PATENT OFFICE VARIABLE AREA FUEL NOZZLE T Cyril Noon, Bainbridge Township, Geauga County, and Frank C. Bayer, East Cleveland,l Ohio, assignors to Thompson Products, Inc., Cleveland, Ohio, a corporationof Ohio Application September 15, 1948, Serial No. 49,414

1 Claim.

vsure in the fuel supply line is generally relatively low so that in the absence of some provision to enhance the orifice pressure at the fuel nozzle inadequate atomization may result. On the other hand, in the absenceof some means to effect adaptation `at the fuelnozzle to increased supply line pressure as the fuel demand increases, the

character of the spray emitted by the nozzle may be adversely conditioned.

The present invention provides improved expedients for economically and efficiently accommodating the entire range of conditions which are encountered in the supply ofv finely atomized spray of fuel to the burners of a gas turbine or jet engine and which arise primarilydue to variations in fuel demand or pressure and the vconsequent variation in the fuel supply volume.

An important object of the present invention is to provide for supplying finely atomized fuel in a spray having a substantially constant quality throughout a wide range of fuel supply pressure and volume.

Another object of the invention is to provide an improved fuel atomizing nozzle of variable area and which is automatically adjustable as to area proportionate to the fuel supply pressure.

A further object of the invention is to provide a new and improved variable area fuel nozzle structure of simple and economical construction and highly efcient operation.

Still another object of the invention is to provide in a variable area fuel nozzle improved means to assure smooth and uniform operation.

Yet another object of the invention is to provide in an atomizing fuel nozzle improved means to assure that the spray will break clean from the discharge orifice.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying two sheets of drawings, in which: l

Figure 1 is a longitudinal sectional View through a variable area fuel nozzle construction embodying features of the invention;

Fig-ure 2 is a longitudinal sectional view of the same fuel nozzle as shown in Figure 1 but with the relatively movable parts in the condition assumed during operation;

Figure 3 is an end elevational view of the fuel nozzle of Figure 1 looking toward the left or'rear end of the nozzle as shown; Y

Figure 4 is a side elevational view ofthe port` insert member of the fuel nozzle; Y

Figure 5 is a transverse sectionalview taken substantially on the line V-V of Figure 1; Figure 6 is a transverse sectional View taken substantially on the line VI-VI of Figure 4;

Figure 7 is a longitudinal sectional View of a modied form of the variable area fuel nozzle;

Figure 8 is a fragmentary longitudinal sectional view through Ya further modified form of the fuel nozzle;

Figure 9 is a transverse sectional view taken substantially on the line IX-IX of lFigure 8;

Figure 10 is a fragmentary longitudinal sec# tional view through a still further modified form of the fuel nozzle; and

Figure 11 is a transverse sectional detail view taken substantially on the line XI-XI ofl Fig-- ure 10.

' In producing a finely atomized spray having a definite shape when introducing fluid fuel to the burners of a gas turbine or jet engine or the like, according to the present invention, the fiuid fuel is forced under pressure from a fixed orifice of predetermined aperture side and length, and immediately before the fluid enters the orifice a strong swirling motion is inducedtherein. As a result a hollow `and conically shaped spray pat"A tern is'created rather' than merely a jet. This is accomplished by having the fluid enter tangentially into a cylindrical swirl chamber immediately upstream from the orifice so that the uid is in rapid rotary motion as a'vortex aboutthe axis of the orifice where it enters the orifice and accelerates due to the constriction affordedvby the orifice, leaving the orice with a violent, 'ex'- panding spiral motion which insures the desired hollow conical shape in the spray pattern an thorough atomization of the fluid. A

In order to maintain the atomization quality of the hollow, conical spray pattern substantially constant throughout a large variable range of fuel demand, the area of the swirl chamber is varied in substantially direct ratio tothe fueldemand or pressure. To this end; the area of the swirl chamber is increased in proportion to the pressure of the fuel supplied to the orifice, and at the same time the volume of fluid supplied to the swirl chamber is increased. As a result the swirl rate, that is, the speed with which the fluid rotates in the swirl chamber remains substantially the same throughout the variable fluid supply pressure range, and while the amount of fluid emitted from the spray orifice will vary accordingly and thus provide a lean or rich fuel mixture as required, the hollow, conical spray pattern will persist throughout the variable range.

In a preferred form of variable area nozzle for practicing the present invention and as shown in Figures 1 to 6, inclusive, a nozzle assembly I5 includes a housing or body I6 of elongated preferably generally cylindrical form including a larger diameter rear portion Il, a smaller diameter forward end portion I8 and an intermediate lateral flange I9 which is preferably formed with a series of peripheral wrench faces 28 (Figure 3) Through this arrangement, the nozzle assembly is adapted to be mounted in the wall of a burner r in the wall of a fuel supply mechanism housingwith the rear portion I1 secured in place through the medium of external threads 2 I thereon by which it is adapted to be threaded into an appropriate aperture or cavity in the supporting wall. The flange I9 may be driven against the supporting wall in the fully tightened relationship of the body I6 when mounted, and the wrench faces facilitate the tightening operation through the medium of a suitable wrench. In this mounted condition of the unit I5, the forward nozzle portion I8 extends as a nose to a substantial extent into the, burner chamber or through a port in the wall of such chamber, depending upon the particular construction and arrangement of the burner.

Fluid fuel is introduced through the rear end of the nozzle housing I6 and discharged through the forward end, the discharged fluid being emitted from an orifice 22 coaxial with the housing I E and of a preferred predetermined diameter and length. In the present instance the orifice is formed in a plate 0r plug 23 which is fitted in the outer end of and sealingly closes such end of a cylindrical bore 24 of larger diameter than the orifice 22 but of smaller diameter than a cylindrical bore 25 in the body nose portion I8 and which accommodates in snugly press-fitted relation an insert sleeve or port member 2'I within which the coaxial bore 24 is formed. The sleeve insert v2I is preferably approximately as long as the nose portion I8 and the bore 24 extends the full length of the sleeve.

Normally completely filling the sleeve bore 24 and bearing endwise in fluid sealing relation against the innerface of the orifice insert 23 about the orifice 22 is a fluid control plunger or piston 28 which is vreciprocably slidable in the bore 24. At its rear end, the piston 28 is preferably formed with an enlarged radial concentric flange 29 about the rim of which is sealingly secured an end of a Sylphon bellows 30. The flanged rear end 29 of the plunger and the Sylphon bellows 30 are accommodated freely and with substantial peripheral clearance within an enlarged bore 3I within the rear portion II of the nozzle housing or body I6 and which merges at its forward end with the smaller diameter bore 25 in the nose portion I8. At its rear end the Sylphon bellows 30 is secured in sealing relation to an annular radial flange 32 at the inner end of a closure plug 33 .which is preferably threadedy secured into the rear extremity of the rear tubular portion II of the nozzle body, the latter being internally threaded as at 34 for this purpose.

An annular series of longitudinally extending fluid bores 35 extending through the plug 33 (Figures 1, 2 and 3) open into an annular radially outwardly opening groove 31 in the inner end portion of the plug immediately behind the bellows attachment flange 32 and which provides a fluid entry clearance into the chamber afforded by the enlarged rear bore 3I of the nozzle housing. Through this arrangement, fluid pressure developing in the chamber within the bore 3| is adapted to `act upon the exposed shoulder afforded by the inner or base flange 29 of the piston to compress the bellows 3lland force the piston 28 rearwardly, whereby to open a forward end portion of the sleeve bore 24 forwardly of the piston and behind the orifice insert 23.

Predetermined resistance to the action of the fluid pressure tending to drive the piston 28 rearwardly is afforded by biasing means such as a helical compression spring 38 of substantially smaller diameter than the internal diameter of the bellows 30 and bearing at its forward end against the rear face of the piston flange 29 about a coaxial spring centering boss 39. At its rear end, the spring is seated against the inner or forward end of a spring tension adjusting screw 46 which is threaded into a coaxial 4I in the plug 33 and has a coaxial spring centering boss tip 42. The bore 4I is preferably of somewhat larger diameter than the spring 38 so as to clear the same for free compression and expansion action in operation.

By tightening or loosening the screw 40, adjustment in the compression of the spring 38 may be effected, and thus the fluid pressure necessary to unseat the plunger or piston 28 from the orifice member 23 appropriately adjusted for optimum results in operation of the nozzle. For convenience in effecting adjustment of the screw 40, it is provided with a head 43 accessible at the rear of the plug 33 and formed with means such as a screwdriver slot 44 to facilitate adjustment manipulation thereof. The diameter of the head 43 is preferably smaller than the diameter of the circle described by the fluid passage bores 35 so as tomaintain the mouths of the latter clear.

Fluid leakage past the adjustment screw 40 is avoided by fluid sealing means such as appropriate O-ring sealing gasket means 45 accommodated within a rabbet groove 4l at the rear end of the plug bore 4I and in sealing engagement between the wall of the groove 4'I and a cylindrical collar 48 on the screw 40 intermediate the head 43 and the threaded shank of the screw. z

Pressure relief for the chamber within the bellows 30 is afforded by a small diameter vent or a relief bore 49 which extends coaxially through the piston 28 to afford communication between the ends of the piston and thereby between the bellows chamber and the orifice 22. In this Way, the piston 28 is adapted to move freely reciprocably, the spring 33 affording spring bias, in conjunction with whatever inherent spring bias may exist in the bellows 30, tending normally to drive the piston into orifice blocking relation (Fig. 1), and the pressure of the fluid in the chamber afforded by the bore 3| tending to overcome the spring bias and drive the piston to orifice unsealing or opening position (Fig. 2). The piston assumes an operative position as determined by any particular balanced condition that may be attained between the fluid pressure and the spring bias.

From the chamber 3|, fluid passes forwardly through the nozzle housing nose portion I8 by way of a pair of longitudinal fluid passages 50 (Figures l, 2 and 5) afforded by longitudinally flatted opposite parallel side portions 5I on the sleeve 21 and the opposing wall of the bore 25. At their forward ends, the fiuid passages 50 communicate with an annular distribution groove 52 in the periphery of the sleeve 21, the forward or outer wall of the groove being defined by a closure head flange 53 on the sleeve (Figures 1, 2

and4).

Communication between the distribution channel or groove 52 and the sleeve bore 24 is afforded by a plurality of ports 54a, 54h, 54e, and 54d, which are directed from the distribution channel 52 inwardly tangential to the Wall of the sleeve bore 24. Bypreference, the several portsiare provided in a series of annularly disposed axially spaced groups to become progressively uncovered as the piston 28 is moved rearwardly by fluid pressure in the nozzle. Furthermore, in order to accommodate an increasing volume of fiuid substantially in proportion to the increase in pressure, the successive series or groups of ports are preferably of progressively increasing diameter and thus of increasing flow area.' To this end, each of the groups of ports may be of equal number,.such as three as shown in Figures `5 and 6, for example, the ports 54a being of the smallest diameter and thusv of the lowest total crosssectional flow area, and located adjacent to the forward side of the distribution groove V52 and spaced a relatively short distance rearwardly from the inner face of the orifice insert 23. The sets of ports Elib, 54o, and 54d are of progressively larger diameterV and thus total cross-sectional fiow area in the order named and are located in appropriately spaced relation, one group to the other in the order named front to rearwardly of the first group of ports 54a. yIn` each group the ports are circumferentially equidistantly located. Furthermore, each of the groups of ports is preferably staggered with respect to at least the adjacent group or: groups of ports, and their spacing is such that fluid entering therethrough into the sleeve bore 24 provides generally overlapping streams with the streams of theadjacent groups of ports, considered longitudinally of the sleeve bore.

VIn operation, until the fluid pressure in the nozzle assembly l5 andmore particularly Within the chamber 3l attains a value sufficient to overcome the spring bias on the piston 28 to move the piston enough to uncover the first set or group of tangential ports 54a, the nozzle remains shut off by the sealing relation of the vforward tip of the piston 28 against the orifice insert 23, whereby the orifice 22 is closed against fiuid discharge and atomization. When the piston has been moved by the automatic action of the fiuid pressure to uncover the first set of ports 54a, the pressure forces the fiuid from the distribution channel 52 through the ports 54a and into the area forwardly of the forward tip of the piston 28 and behind the orifice insert 23 serving as a swirl chamber 55 (Figure 2) In the swirl chamber, the fluid entering tangentially under the substantial force of the main body of the fluid, and after developing substantial velocity in passing through the relatively small first ports 54a, whirls around at high velocity in a spiral, vortex path to the entrance to the orifice 22 intowhich it passes as a tubular column with substantially undiminished or increasing whirling velocity and under pressure resulting from the orifice restriction. From the mouth of the orifice 22 the fluid, spinning at high velocity, is projected as a finely atomized hollow cone-shaped spray stream.

As the fluid pressure increases the plunger or piston 28 is moved successively further rearwardly and successively uncovers the sets of ports 54h, 54e, and 54d depending, of course, upon the fluid pressure and remaining at any intermediate open position shouldthe uid pressure and the spring bias attain a substantially balanced relationship. As the swirl chamber 55 enlarges in area in the progressive pressure induced retreat of the piston 28, increased volume of iiuid enters the chamber in proper proportion to maintain substantially constant fluid velocity at the orifice 22. This assures that the atomization quality of the spray stream from the nozzle will remain substantially constant even though the volume of fluid emitted in the spray stream may vary from time to time throughout the entire variable area range afforded by the several sets of ports and the variable area swirl chamber 55.

Fluid sealing and dirt catching means may be provided in the form of a series of parallel annular grooves 51 in the periphery of the plunger or piston 28 spaced from the forward tip there- In order to insure that the spray stream from the orifice 22 will break clean-and not tend to run along the face of the orifice member 23 due to adhesion, a lip or extension 58 is provided to project forwardly from the orifice insert 23 about the mouth of the orifice 22. This lip or extension 58 forces the fluid to break away from thesurface of the orice member and form a more distinct spray cone.

In the modification of Figure '1, a nozzle assembly 53 is shown including an elongated hollow body yor casing member 60 within the forward portion of which is a relatively large diameter bore 6| providing a fluid chamber into which leads an inlet port 62 from one side of the casing or housing and defined by an inlet boss 63. At its forward end, the chamber 6I is closed by an orifice plate 64 having an axial orifice 65 defined by a protruding lip 61.

The chamber 6| is of larger diameter than a sleeve member 68 which is mounted on the inner face of the orifice plate 64 'and has a bore 63 concentrically related to the orifice and of larger diameter. Within the bore 69 is a plunger 10, the forward end of which is normally adapted to, bear against the inner face of the orifice plate 64 in sealing relation to the orifice 65. At its rear end, the plunger 10 is provided with an enlarged diameter portion 1| which is slidably guided as a piston in a reduced diameter section 12 of the housing bore. Biasing means, such as a coiled compression spring 13 bears against the rear end of the piston portion 1l and is in engagement at its other end with a closure plug 14 which closes the rear end of the body bore. 'I'he plug 14 is adjustably threaded into the body bore so as to adjust the tension of the spring 13. y

In its orifice sealing position under the infiuence of the biasing spring 13, the plunger 10 has an intermediate generally `frusto-conical, poppet valve portion 15 sealingly seated against a valve seat 11 provided by a ported barrier plate 18 disposed intermediate the inlet 62 and the rear end of the` plunger guide sleeve 68. Rearwardly ofthe valve portion the plunger has a cylindrical portion of intermediate diameter identified at 19 and which merges with the cylindrical piston portion 1| on an annular forwardly facing shoulder 80.

In operation of the form of Figure 7, fluid entering through the inlet 62 is trapped in the chamber between the barrier wall 18 and the opposing shoulder at the mouth of the reduced diameter bore portion 12 and the piston shoulder 80. When the pressure of the fiuid is greater than the pressure exerted by the biasing spring 13, the piston portion 1| is moved rearwardly and thus causes the valve portion 15 to leave the valve seat 11 whereby to crack the valve and at the same time the plunger 10 moves away from the entrance to the orice 65. The fiuid escaping past the valve seat 11 into the bore chamber 6| is delivered by way of radial or tangential ports 8| of relatively small diameter and thus small aggregate cross-sectional fiow area adjacent to the forward end of the sleeve 68 into the forward swirl chamber portion of the sleeve bore 69 where, similarly as in the swirl chamber 55 (Figures l and 2), the fluid swirls with sufficient acceleration to travel in a vortex flow to exit through the orifice 65 from which it is emitted as a hollow cone-shaped atomized spray stream. Greater pressure of the fiuid entering the nozzle assembly further unseats the plunger 10 until a series of ports 82 of larger diameter is uncovered to afford increased fiuid volume in the increased area of the swirl chamber. Still further opening movement of the plunger 10 uncovers a series of ports 83 disposed successively after the ports 82 and of larger individual diameter and aggregate crosssectional flow area and further increasing the volume of fiuid entering the greatly increased area of the swirl chamber portion of the bore Pressure relief for the chamber area behind the plunger piston 10 within which the biasing spring 13 is operative is afforded by way of ya relief bore 84 of relatively small diameter extending through the axis of the plunger 10 and affording a passage from the rear end through the forward end of the plunger and in operation venting into the rear part of the swirl chamber which due to the vortex iiow existing therein vdoes not fill up toward the rear and thus affords a clear vent passage.

'While the forms of the invention shown in Figures 1 and 7 provide for sealing off the spray orifice, either at the orice or at a point between the inlet into the nozzle and the orifice or at both' places, certainv conditions may require that there be a constant minimum' fiowA passage between the fluid chamber within the nozzle and the orifice. For this purpose the form of the in-` vention shown in Figures 8 and 9 may be desirable. In this form a nozzle' assembly 85 including a tubular housing or casing 81 providing an enlarged fiuid chamber 88 has an inlet 89 for delivery of fluid into the chamber B8 and an end closure 90 with an axial discharge lorifice 9| defined by a protruding annular lip 92.. A sleeve 93 of smaller external diameter than the internal diameter of the chamber 88 abuts the closure wall 90 and affords a sliding guide for a reciprocable fluid control plunger 'or piston 94. Appropriate biasing means which may be of either of the forms shown in Figures 1 or `7, or any other appropriate arrangement, normally maintains the forward end 'or' tipof the plungery 94 in abutment with the inner face of the closure Wall about the entrance to the orifice 9|.

In order to by-pass the forward tip of the sleeve 93 for minimum fiuid delivery from the chamber 88 to the orifice 9|, the inner face of the closure wall 90 is formed with a set of shallow inwardly radially extending fluid delivery grooves herein shown as four in number (Figure 9) and extending tangentially to the orifice 9|. The grooves 95 extend from beyond the periphery of the tip of the sleeve 93 and thus aord constant communication of small aggregate fiow area between the chamber 88 and the orifice 9| so that fluid will be delivered to the orifice 9| even though pressure may not be great enough to unseat the plunger 94 to open communication between the chamber 88 and a swirl chamber within the forward end portion of the sleeve 93 by way of a set of radial or tangential ports 91 opening through the sleeve. By preference the ports 91 are of substantially larger aggregate flow area than the grooves 95. As the pressure increases, the plunger 94 is unseated further until a second series of ports 98 in the sleeve 93 is uncovered. A further increase in pressure may drive the plunger 94 open to the extent that a final set of ports 99 will be open as the area of the swirl chamber increases. Through this arrangement, a swirling supply of fiuid is delivered to the orifice 9| as long as there is any fiuid pressure within the nozzle, and it is not necessary that a predetermined pressure build up within the nozzle before fiuid is delivered as a spray from the nozzle. As the pressure increases, of course, the swirl area for the orifice 9| increases proportionately as does also the volume of fiuid delivered to and through the orifice.

For certain purposes it may be highly desirable to effect a thorough fiuid seal between the tip of the movable plunger and the orifice of the nozzle so as to avoid any possibility of leakage or dripping. For such purposes, the form of the invention shown in Figures 10 and 11 may be desirable. In this form a nozzle |00 having a body or casing |0| formed with a fiuid chamber |02 has a closure plate or disk |03 across one end thereof and formed with an axial spray orifice |04. Integral and concentric with the closure member |03 is formed a sleeve boss |05 which projects inwardly and forms a tubular guide for a plunger or piston |01. At its forward end or tip the plunger |01 is formed with an axial frusto conical tappet valve projection |08 which in the fully seated condition of the plunger tip engages sealingly with a tapered valve seat |09 formed about the entrance to the orifice |04. Suitable biasing means, such as that shown in Figures l or 7, vor any other preferred form of biasing means may be utilized for normally urging the plunger |01 into the sealing rennen reianve to the orifice |04. As in the previous forms of the invention described herein the plunger |01 may be provided with an axial small diameter bore providing a vent passage ||0 which is coaxial with and vents toward the orifice |04.

Rearwardly of the valve tip of the plunger |01 the sleeve |05 is provided with fiuid delivery port means communicating with the chamber |02. To this end, the sleeve |05 spaced a predetermined short distance from the plunger tip seat is formed with a pair of longitudinal slots tangential to the wall of the inner bore of the sleeve. The slots may be of any preferred width and length and although shown as two in number may be in any other preferred number equidistantly spaced circumferentially. Thus, when sufficient pressure has been built up within the chamber |02 to unseat the plunger to the extent that the tangential slot ports are uncovered iluid will issue into the swirl chamber defined between the forward end of the plunger |01 and the orice |04 and accelerate as a vortex which ows through the orice |04 to eiect a finely atomized hollow cone spray. As the plunger |01 is moved rearwardly to increase the area of the swirl chamber, there is proportionate increase in the orifice area as the plunger progressively uncovers the port slots On the other hand, of course, there is a proportional diminution in the port slot area as the area of the swirl chamber decreases as the pressure of the fluid drops and the plunger |01 returns toward its sealing relation about the orice |04.

It will. of course. be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claim.

We claim as our invention:

A nozzle comprising a generally tubular housing, a member disposed in said housing adjacent one end thereof and having a, longitudinal bore therethrough, said member having a longitudinally extending recess in the outer surface thereof dening with a facing portion of the inner surface of the housing a flow passage and having a transversely extending port between said recess and said bore, a flow control plunger having a portion slidable in said bore and normally closing said port and having an internal terminal end, said plunger being movable. in a direction away from said one end of said housing for opening said port, a plug detachably secured in said housing adjacent the other end thereof and having an inlet port extending longitudinally therethrough, said plug having an inner terminal end longitudinally spaced from the inner terminal end of said plunger, a generally cylindrical flexible bellows sealingl'y connected at one end to said terminal end of said plug and at the other end to said terminal end of said plunger, the outer surface of said bellows being inwardly spaced from the facing inner surface portion of said tubular housing and defining therewith a fluid flow passageway communicating with said inlet port and said passage, said bellows being compressed by iiuid under pressure from said inlet port to move said plunger longitudinally away from said one end of said opening and accommodate fluid flow through the nozzle.

T CYRIL NOON. FRANK C. BAYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Ser. No. 330,226, Anxionnaz et al. (A. l?. C), published May 25, 1943. 

